Sound reproducer of talking machines



Dec. 11 1923. 7 1,476,928

I c. SCRABIC SOUND REPRODUCER TALKING MACHINES Filed Ami; 5. 1.922

( naw/Mow Patented Dec. ll, T23.

U N IT E S T A T E CARL SCRABIC, or unnana, OHIO.

sonun nnrnonuonn or TALKING iuacmnias.

' 7 Application filed A ril 3,

a specification.

This invention relates to improvements in the sound reproducers of talking machines, and has particular reference to an improved mounting for efiecting the vibratory retention of the diaphragm within the 7 sound creating chamber of a reproducer, the

primary object of the invention being to provide in the reproducer a diaphragm which will be subjected to circumferential pressure for the purpose of maintaining the diaphragm under tension and to thereby render the same properly responsive to the vibratory movements of the stylus.

In accordance with the invention, there is provided a sound reproducer in which its diaphragm is surrounded by a pair of wedge shaped rings which upon being forced together into operative relationship within the reproducer, will contact circumferentially around the peripheral edges of the diaphragm, so that the latter will be placed under sufficient tension to vibrate in harmony with the stylus and to reproduce the/slightest vibration or movement on the part thereof.

The invention broadly consists in the provision of a dia hragm for a sound reproducer which wiil be maintained under suitable tension while positioned for operation within the reproducer.

F or a further understanding of the invention, reference is to be had to the following description and to the accompanying drawing in which:

E igure 1 is a side elevation of a talking machine reproducer formed in accordance with the present invention.

Figure 2 is av vertical transverse sectional view taken on the plane indicated by the line 2-2 of Figure 1.

Figure 3 is a perspective view of the inner split clamping ring of the diaphragm, and,

Figure 4: is a similar view of the outer ring.

Referring more particularly to the details of the invention, the numeral 1 designates in its entirety the sound box or reproducer of a talking machine, the same in this instance being formed to comprise a substan- 1922. Serial No. 548,978.

tially circular casing 2, wherein is formed a rear wall 3, having an axialopening 4 provided therein by means of which'the internal sound creating chamber 5 within the casing will be in communication with the amplifying appliances, now shown, of the machine. In this instance, the wall 3 is reduced as at 6 contiguous to its outer edge, and is formed to provide angularly extending rim 7, defining the boundary of the chamber 5. Between the reduced portion 6 of the casing and the opening 4, the

rear wall is comparatively thick for the purpose of confining sound vibrations within the chamber 2 and preventing their undue escape to the atmosphere, as would happen.

if the rear wall was uniform in thickness with the reduced outer portion 6. Also, by reducing the rear wall as at 6, it is possible to form the casing readily and with suitable tools to produce a substantially circular rim 7.

The lower part of the casing includes a depending web 8 which serves to pivotally receive the outer ends of an axially rotatable stud 9 upon which the stylus or diaphragm arm 10 of the sound box is rigidly mounted for oscillation. The lower end of the stylus -is provided as usual with a socket for the reception of an interchangeable needle 11, which is held in place by means of the ordinary thumb screw 12. The construction for effecting the pivotal mounting of the stylus is not pertinent to this invention. The upper end of the stylus is reduced as at 13, and is terminated in an angularly bent extremity 14, which is secured to the axial portion 15 of the diaphragm 16. Preferably, this diaphragm is formed from a thin metallic or blank composition suitably shaped in accordance with the disclosure set forth in my copending application bearing Serial Number 456,046A, filed March 28, 1921.

outer by the numeral 18. The ring 17 is splitand of slightly greater diameter than the diaphragm 16 so that the latter will be r positioned cent-rally within said inner ring,

as shown in Figure 2. If desired, I may form the inner wall of the inner ring with inwardly p-rojectin studs 19, having their inner end forme with substantially V shaped notches 20 into which the peripheral edge of the diaphragm 16 extends, the sloping walls of said notches serving to securely seatthe diaphragm therebetween when compressive pressure is applied to the diaphragm, the said studs serving to space the peripheral portions of the diaphragm from the inner wall of the ring 17 so that the dia- 'phragm will be permitted to vibrate-freely without being hindered b the association of the ring 17 therewith. urthermore, by the provision of the V shaped notches in the studs, the diaphragm will be properly centered within the central portion of the ring 17 and prevented from moving laterally.

To place the diaphragm under tension, the said inner ring is provided with an outer inclined surface 21 which forms the ring 17 so that the portion'thereof in engagement with the wall 6 will be thicker than the corresponding outer portion or edge. Similarly, the outer'ring 18 :has its inner surface inclined as at 22 to correspond "with the .inclined outer surface 21 of the inner ring, but the edge ofthe outer ring 18 in engagement with the wall 6 is narrower than the corresponding outer edge or surface thereof. The outer ring is formedwith openings suitably spaced thereabout, and these openings are adapted to receive screws or other similar fastening elements 23, which are threaded preferably into the wall 6. Manifestly. by tightening the screws 23, relative approach between theinner and outer rings may be effected, so that when said rings are finally positionedwithin the chamber 5 and. in substantially the position shown in Figure 2,-the inner ring will have its studs 19 forced into compressive engagement with the peripherall edge of the diaphra m 16, placing the latter member under a s cient degree of tension toadmit of ve sensitive vibration on the "part thereof an to enablethe same to properl interpret the vibrations imparted thereto y the stylus or diaphragm arm 10. Preferably, the diaphragm is formed from metal, and its thickened outer edge enables the same to withstand properly "the compression of the clamping rings without unduly bends ing or bulging the center of the diaphragm from its true operative position. By reason of thematerial from which it is formed, and

the tension imparted to the diaphragm by the clamping rings, the samewill .be rendered exceptionally resonant and capable of setting up harmonic sound disturbances or waves within the chamber 5. If desired, the peripheral edge of the diaphragm will be confined between rubber or other similar non-resonant gaskets 24, which will serve to insulate the diaphragm from the adjoining metallic parts of the reproducer. By the construction described, it will be observed that the diaphragm will be capable of vibrating after the fashion of a taut string ofa musical instrument. While I have de scribed and shown a diaphragm of peculiar formation, never-thc-less it is to be understood that any form of anordinary diaphragm may be utilized in lieu thereof for example, a mica, or composition diaphragm. Similarly the studs 19 may be supplanted by a circular rib extending completely around the inner surface of the split clamping rin 17.

hat is claimed is:

1. In a sound box, a casing including a chamber, a diaphragm mounted for vibration within said chamber, a pair of wedge shaped clamping rings urrounding said diaphragm, and means projecting inwardly from the inner of said rings and disposed for engagement with the peripheral edge of said diaphragm.

2. In a sound box, a casing including a chamber, a diaphragm mounted within said chamber, inner and outer clamping rings surrounding said diaphragm and of substantially wedge shaped formation, whereby upon relative approach between the said rings, said diaphragm will be placed under tension, and fastening devices between one of said rings and said casing. 3. In a sound box, a casing formed to in-. clude a chamber, a diaphragm mounted within said chamber, inner and outer wedgeshaped clamping rings positioned within said chamber and surrounding said diaphragm, studs projectin inwardly from the inner of said rings and disposed for engagement with the peripheral edge of said dia phragm to space the latter from said rings, and fastening devices between the outer of said rings and said casing, and serving to effect relative approach between said rings to place said diaphragm under tension.

4.1m a-sound box, a casing including a chamber, a diaphragm mounted for vibration within said chamber, a pair of clamping rings surrounding said diaphragm, and

spaced means projecting inwardly from one 

